The present invention relates to a method and device for detecting target elements. In particular, the present invention relates to surfaces coated with target-specific compounds which produce a detectable signal when bound to the specific target.
A sensitive and rapid detection of trace amounts of toxic elements remains a highly desired objective in providing better human health related to dietary consumption and ingestion derived from agriculture and related food industries. The use of selective and sensitive fluorescent sensory systems for such applications has attracted considerable attention. For example, optical chemosensors with a built-in fluorescence transduction mechanism capable of recognizing specific analytes or target elements in a complex sample matrix have been rationally designed and executed. Both non-ionic and ionic analytes such as sugars, citrate, metal ions, amino acids, creatinine, tripeptides and proteins have been selectively targeted with designed fluorescent compounds.
Recently developed nanoparticle technology possesses a unique feature of higher surface to volume ratio, which affords a significant signal enhancement for detection of biological molecules when the nanoparticles are used as fluorescent signaling reagents in solution (Chandler and Chandler, U.S. Pat. No. 6,649,414; Tan et al, U.S. 2004/0067503 A1). These nanoparticles can be incorporated with a large number of dye molecules to enhance the emission of strong fluorescence signals. However, the fluorescent nanoparticles described in the literature to date have only been used in solution reactions that require separation of the nanoparticles before detection to remove those non-reacted fluorescent nanoparticles. Further, in comparison with the chemical sensors in which detection occurs with a solid sensing platform, the sensitivity using nanoparticles is substantially slower. Therefore, it would be of considerable benefit to devise a detection method that provides increased sensitivity of nanoparticles without requiring additional processing steps or time for binding or separation. The invention described herein is able to resolve both of these limitations in the rapid analysis of trace elements important in human health.